Deep Air Question

[tombiowami]

I have never had the pleasure or displeasure of being narced but have a couple questions.

From what I have read, nitrogen at depth mimics the properties of nitrous oxide.

Would any deep air students out there dive to say 30' and then switch to a tank that contains nitrous oxide?

If not, why would you go to 150' and do it?

I just had my wisdom teeth out, and the feeling from that nitrous was not pleasant, quite anxiety inducing actually, buzzing, numbness, etc.

What am I missing? I can understand, kind of, diving deep air just because you want to, but why take specific training to do it when you could just as easily take a trimix class?


Tommy

[WreckWriter]

My reasons for diving air deep were always economic. now that finally got my trimix course done I will no longer dive deep air by choice.

Tom

[GP]

Yeah...deep air is dumb.:rolleyes: :confused: :boom:

[Wendy]

Probably a lot of folks that dive deep air think that they aren't narced. Just like the drunk that thinks he is fine to drive, he just doesn't know how impaired he really is. I'll probably get flamed for saying that though.

[tombiowami]

I was recently talking with a guy who had taken the course and the impression I got was that they went down to 150' to make sure they were narced and then practice certain rote skills.

The thinking was that by practiciing over and over they could eventually overcome or work within being narced.



Tommy

[trheeltek]

I dive deep air mainly for economic and logistical reasons - it's cheaper and easier to get than trimix. I do like doing it, as long as the profile's pretty easy; it's a risk/reward thing. I feel comfortable enough at depth to tolerate the risk. For you, the risks seem to break down differently - wouldn't say you're missing anything, it's just a different approach. Why not try it with someone you trust who's done it and see what it's like - a few of the wrecks off NC hit 140' (the Naeco does, I think).

For the record, I've never been on nitrous oxide, but those I know who have been seemed a lot loopier than I've ever been at 150'.

[tombiowami]

So if I said I was going to dive to 30' and then breathe nitrous, would you say that is Ok?

Why or why not?

Tommy

[WreckWriter]

I have no idea what's involved in a deep air class. I never had specific training for it, just worked my way slowly and steadily downward until people started looking at me funny <shrug>

I personally don't feel that 150' is excessively deep even on air. I wouldn't want to do it now, since I no longer have to, but have done so many times with no appreciable discomfort. For myself I always felt that I was leaving the realm of safety at about 200'.

In recent years I've been well aware that deep air was not the way to go but it was always a lot of money that I didn't have to get mix certification. My guess is that most deep air divers feel this way.

As far as what Tommy said about being able to take trimix instead of deep air I'm not sure that's always possible unless you have enough experience for the instructor to bump you past some of the prerequisites. I guess that would depend on the agency.

Tom

[MikeFerrara]

Lets all flame Wendy!...just kidin

I don't dive with anyone who approves of deep air but they certainly have different definitions of what deep air is. I know divers who were going well in exess of 200 for years before anybody had mix. They don't do that anymore but they roll their eyes when you try to tell them they shouldn't do 150 after they have done accurate serveys at 300. They may have been impaired but the fact is they have done on air at 300 what most can't do at 30 so who is impaired. Your performance will not be its best but what about those who are not so good anywhere.

A really good driver may outdrive a bad driver even when under the influence. When deciding what impairment can be tolorated maybe you need to take the baseline into consideration.

Me, I use mix.

[WreckWriter]

MikeFerrara once bubbled...
I know divers who were going well in exess of 200 for years before anybody had mix.

Good point. I think a lot of people who are so quick to talk down deep air divers were not around when there was nothing else. Trimix really hasn't been commonly available for very long, neither the training or the gas.

Me, I use mix too but the days of old are still fresh in my mind.

Tom

[Rick Murchison]

I don't think anyone here will dispute the physiological or safety advantages of trimix over air for dives over 100' or so. Trimix is clearly safer in every way.
But... when looking at diving the site or not, with air the only gas available, the go/no-go depth suddenly deepens. It's a matter of acceptable risk. I would never urge anyone to accompany me on air below 110', they'd have to ask. But as FredT has so eloquently explained in an earlier thread, there are ways to reduce the risk to an acceptable level. Planning, training, training and planning. And planning.
Rick

[Ontario Diver]

WreckWriter once bubbled...
I have no idea what's involved in a deep air class.

The IANTD or TDI Deep Air Class is more about deco diving beyond the NDL time limits not as much as the depth limits. But they do cover the O2 Tox and Narcosis in detail. There was definately a flavour of "More Time = Deco & More Depth = Trimix" on the course.

[WreckWriter]

Rick Murchison once bubbled...
But... when looking at diving the site or not, with air the only gas available, the go/no-go depth suddenly deepens.

Bikini is a perfect example. Spectacular wrecks but only air. Would you go? I sure would....

Tom

[Spectre]

tombiowami once bubbled...
Would any deep air students out there dive to say 30' and then switch to a tank that contains nitrous oxide?

If not, why would you go to 150' and do it?


Nitrous oxide is not the same as air at elevated partial pressures. It's a chemical compound N2O. It's _much_ different then air [79% N, 21% O2 in the case of 'hyper' air].

Nitrogen is an inert gas in your respiratory system. You can't breathe water [H2O], so what makes you think you can breathe N20?

The problems with breathing nitrous is that you have to 'cut' it with O2... if you take a 50% breath of N20, then 50% breath of air, you're getting 10.5% 02, which is hypoxic.

And even if you created a mix with N2O and O2 to enable breathing, what about decompression...

[MikeFerrara]

Hey all,

With respect to something I said in my last post...

A really good driver may outdrive a bad driver even when under the influence. When deciding what impairment can be tolorated maybe you need to take the baseline into consideration.

My intention was not to condone or encourage driving drunk or diving narced. We should be sharp and at our best when we dive and for that matter when we drive. The point I was trying to make is that we should not be so quick to judge others because they have set different limits for themself than we have for ourselves. Hope nobody misunderstood.

[noshow]

if you are DRUNK you are DRUNK... if you are NARCED you are NARCED...

So the trucker who spends his life on the road driving is ok to drive DRUNK and is less likely to kill someone than the rookie DRUNK driver? "I'm only a little drunk but I won't kill someone tonight, I promise, I'm ok." They ususlly get home but their chances are drasticlaly reduced. Why not cut out the problem and take a cab? A bit of an inconvenience and greater expense but if you want to drink and get home safe, why not?

So the diver who spends his life diving as an instructor is ok to dive NARCED and is less likely to kill someone than the rookie NARCED diver? "I'm only a little NARCED but I won't kill someone this dive. I promise, I'll be ok". They usually get home but their chances are drastically reduced. A bit of an inconvenience and greater expense but if you want to dive deep and get home safe, why not?

It's too simple...

[MikeFerrara]

I sure do regret the analogy I used.

This is an issue that I think everyone oversimplifies. As I said no impairment is better than some impairment. However, there are other sources of impairment both phisical and mental. Many things effect our ability to perform at any given time. Maybe at some depths there are factors that may effect an individuals performance to a greater degree than narcosis. Narcosis seems to get all the attention though.

[WreckWriter]

noshow once bubbled...
if you are DRUNK you are DRUNK... if you are NARCED you are NARCED...

That's obviously a major oversimplification. Sure, if you are..., you are..., but, using the drunk analogy again, don't you think that the guy who had 3 beers is maybe not quite as dangerous as the guy who had 30? Same trick for narcosis, you're not as narced at 130 as you are at 230.

Impared yes, but there certainly are degrees of impairment. That's why you mix based on PO2 and END.

Tom

[MikeFerrara]

I am not in favor of deep air. I am also not in favor of a diver who thinks he is ok at 95 ft but thinks the next guy is dangerous at 105.

[JamesK]

Mike,

Just interested in where you draw the line on deep air. Your statement of 95 compared to 105 feet sounds like a statement made by someone who I was talking to about it. My personal limit is 120 on air. Deeper only in an emergency. When I told this to someone else, they basically made the same statement, well why not 130 or 140 or 150? Well then if not 150 why not 160? My question was "Where does it stop?" I was just wondering what you considered too deep for air. If you already mentioned this, sorry.

[Rick Murchison]

JamesK once bubbled...
Mike,

Just interested in where you draw the line on deep air. Your statement of 95 compared to 105 feet sounds like a statement made by someone who I was talking to about it. My personal limit is 120 on air. Deeper only in an emergency. When I told this to someone else, they basically made the same statement, well why not 130 or 140 or 150? Well then if not 150 why not 160? My question was "Where does it stop?" I was just wondering what you considered too deep for air. If you already mentioned this, sorry.
The question as posed has no real answer, for the answer depends mightily on
(1) for how long?
(2) under what conditions?
.....(a) temperature
.....(b) visibility
.....(c) current
.....(d) hazards
(3) to do what? Just have a look? Perform a complex task? Explore? Inside a wreck or cave? Recover something? etc...
(4) with whom?
(5) with what support?
(6) with what equipment?
(7) how am I feeling today? Healthy? Rested? Hydrated?
(8) myriad other miscellaneous factors
The answer for me can vary from "just stay home" to 218' - where I hit my personal absolute deep air diving oxygen exposure limit of 1.6 ATM (and that can start a whole new line of argument).
Rick

[MikeFerrara]

There you go James, put me on the spot why don't ya.

BTW, I like the picture in your profile. I have pictures taken, I believe, on that very rock.

The trining that I have valued the most and place the most faith in has been my cave training. I accept the rules derived from accident analysis which state max depth (end) of 130. However, there are shallower dives that I won't do without mix.

So...I think an end of 130 is too deep for some dives and some divers. The dives that scare me the most are when new divers go to 120 in Cozumel using rental equipment following a DM. At these depths there are, IMO, bigger issues than narcosis. You need more than helium. I really hate it when a diver who goes to 100+ with minimal training, experience and equipment wants to lecture (or judge) others about narcosis. IMO, this is the perfect example of the pot calling the kettle black.

Read and give some thought to rick's post

[JamesK]

WOW! Great answers from both of you guys! Thanks!

BTW, sorry to put ya on the spot Mike! ;)

I agree 100% with you about the Caribbean thing. That to me is just plain ridiculous, and dangerous.

Thanks for the compliment on the picture. My buddy and I did some quick pictures last month while we were down in Peacock. That pic is right at the begining of the bedding plane. I think that rock behind me is famous for training! I beleive I did my first lost line drill there!

Anyway, thanks again guys.

[cavediver]

Deep air is stupid

[Cave Diver]

I am currently taking the IANTD Deep Air and Advanced Nitrox courses.

The focus of the classes is NOT to advocate diving deep on air. The absolute max depth is 130' with a working PO2 of 1.4

The focus of this class is about gas management and dive planning. We are learning about the benefits of using up to 50% nitrox to aid offgassing, decompression planning, the use and carrying of stage bottles, etc. There is also more of a focus on equipment consideration such as the use of either an H-valve or doubles with a manifold to provide redundant air supply.

I am not taking this class so that I can go out and do 'deep dives' to more than recreational limits, I am doing it to learn more about the skills and equipment that will be required as I move towards my trimix certification. I think it is rather unfortunate that this class is called 'deep air' because it seems to give people the impression that anyone who is doing it is breaking recognized limits and standards.

Of course, I am sure there are those that are doing just that, but I feel the ones that do break the limits are more likely to be the people who have had the lesser amount of training and don't realize how really stupid and dangerous this can be.

[Rick Murchison]

cavediver once bubbled...
Deep air is stupid
Ah... how deep, Grasshopper???
Rick

[cavediver]

Rick Murchison once bubbled...

Ah... how deep, Grasshopper???
Rick


any depth-- master Rick

[cavediver]

[QUOTE]Cave Diver once bubbled...
[B]I am currently taking the IANTD Deep Air and Advanced Nitrox courses.

Its good that you are going to an ADV level of training. but you learned in nitrox class the advantages of less N2 right. so now you are taking a deep air class with all of the things you mentioned. Deco, extra tanks, more depth etc. thats task loading. and elevated N2 levels add to the risk of problems. one takes a ADV. nitrox or trimix class to take advantage of the gas mixes, less N2. so why go back to OW 101 and dive air again. you dont have to take deep air to advance to higher levels of diving. what are they trying to show you, that you can go deep be narced, and pay for what you aready know, that air has a narc affect the deeper you go. when I took the ADV. nitrox course I skipped right pass the deep air crap, then moved on to trimix

[WreckWriter]

cavediver once bubbled...
[QUOTE]Cave Diver once bubbled...
[B]I skipped right pass the deep air crap, then moved on to trimix

Yep, that's the right way to do it. It's at the instructor's discretion. I actually skipped Adv Nitrox too, went from Nitrox to Adv Trimix (with a few hundred deep dives in between).

Tom

[cavediver]

WreckWriter once bubbled...


Yep, that's the right way to do it. It's at the instructor's discretion. I actually skipped Adv Nitrox too, went from Nitrox to Adv Trimix (with a few hundred deep dives in between).

Tom

I agree Tom it is the instructors choice. if you have been deep , have been exposed to diving with doubles or something that imposes task loading at depth. can prove that you are a competent diver like going to say 60ft in tec gear with the instructor and showing you are "good enough" to advance to a certain stage of training

[Cave Diver]

cavediver once bubbled...
so why go back to OW 101 and dive air again. you dont have to take deep air to advance to higher levels of diving. what are they trying to show you, that you can go deep be narced, and pay for what you aready know, that air has a narc affect the deeper you go.

Maybe you missed the part in my post where I said that the deep air class was not about diving past recreational limits. The focus on the class is the training in the use of stage and deco bottles, advanced gas planning, and considerations that must be taken into account when diving in the 100' range. Since you skipped this class I take it that you already know all there is to know about these consideration, but for myself I prefer to take every opportunity afforded me to gain knowledge.

[MikeFerrara]

Hey everyone,

If we're talking IANTD the course is no longer called "deep air". The title of the course is "Deep Diver". We usually combine this class with Advanced Nitrox or if the diver hasn't had Nitrox yet it can be combined with Nitrox. The max depth is 130. The purpose is to introduce the equipment, skills and plannind required for deep/tech diving. The instructor can give credit for experience but I would have to check the standards to see just what he can do. For most divers to skip this course and go streight to trimix would be impossible. Not because of the gas but because of the skills. The Deep Diver/Advanced Nitrox is often a real shocker. Someone like WreckWriter who has many deep dives in doubles may pull it off. However, there are not many of those.

I have yet to complete a Deep Diver/Advanced Nitrox course in the minimum number of dives. The course is not about the depth, it is about the skills. Once you have Advance Nitrox you can take a combination of the Technical diver and Normoxic trimix and thus never exceed 130 without Helium. You can skip Normoxic trimix (once called intermediate trimix) and go streight to full/advanced trimix however you can't skip the technical diver course (once called technical nitrox). This class taken alone does require you to go past 130 without trimix. Again what credit an instructor can give for experience I'm not sure. IANTD is much smaller than an agency like PADI. I have heard of exceptions being made but they may require getting the ok from Tom or David Mount.

[-BlueHole-]

How deep is deep ?
Depends on too many factors...
in a lake with 5 mt. of visibility and a temp of 4 Celsius 120-140 feets could be deep (on air)
in the sea with 30+mt visib and 20+Celsius 120-140 is not deep
is warmer--breathe less, you see--less stress, so less narcosis less co2 retention, also po2 becomes not so (but remains) dangerous...
probably a warm-clear sea diver will feel more the depth in a lake, and a cold-dark lake diver will feel lees the depth in the sea...

[hitomi316]

i find that Bluehole gave me something to think about. Planning on diving "up north" this fall.............glad you gave me another angle to plan my dives!!:book2:

[DocRCH]

I'm sorta late getting into this thread.The narcosis of deep air and N20 are essentially the same. Currently, the Myer Overton theory of how anesthetic gasses work goes on the basis of lipid solubility of the gas in question. It is thought to make the electrical conduction to be inhibited somewhat. To me, this is a logical description and the data and mechanism seem to "fit". (There is a competing theory with the activity occuring at the synapse. But, this is academic.) Helium is also an inert gas (as far as the biological systems go) and it is used to prevent narcosis. It is not as nearly as lipid soluble as N2 or the anesthetic gasses. As far as diving, I would think that N20 at any depth would be ill advised. Maybe, on the boat after the dive.... just kidding!

Robert:doctor: